In recent years, the use of liquid crystal displays as monitors in televisions and computers has been rapidly widespread. The brightness of a liquid crystal display is regulated by controlling the transmittance of light with a liquid crystal material and a polarizing film (and a retardation film). The liquid crystal material is sealed in between two glass substrates opposed to each other.
In a liquid crystal display, a glass substrate constitutes a region where an image is displayed. Therefore, a defect in the glass substrate leads directly to deterioration in display quality. Examples of the type of defect in a glass substrate include commingling of foreign bodies and generation of bubbles or blemishes. Conventionally, glass substrates produced have been inspected for such defects, and a glass substrate found to be defective has been discarded.
However, in the case of use of only defect-free glass substrates, there is a problem with a decrease in yield. In particular, as increases in screen size of liquid crystal displays have caused large-area glass substrates to be used, it has been difficult to produce large-area glass substrates completely free of defects. Therefore, the yield problem is serious.
In better cases, defects may be found immediately after production of glass substrates. However, in some cases, defects may be found in glass substrates assembled into liquid crystal display panels. In such a case, it is necessary to disassemble a liquid crystal panel whose glass substrate has been found to be defective, replace the defective glass substrate with a defect-free glass substrate, and reassemble the liquid crystal panel; that is, an onerous task is required. Therefore, there have been aspirations for the development of techniques for repairing defective glass substrates.
In face of such a problem, Patent Literature 1 discloses a technique for repairing a defect, such as a pinhole or a void, which has occurred in the front plate of a plasma display. This technique repairs the front plate by applying or filling a glass paste to or into a missing or defective site such as a pinhole or a void.
Citation List
Patent Literature 1
Japanese Patent Application Publication, Tokukai, No. 2000-294141 A (Publication Date: Oct. 20, 2000)